Help patients adjust to dwindling sunlight

This time of year, with the rollback of daylight saving time to dwindling sunlight in late afternoons, Sue Lowe, O.D., quizzes the patients at her Laramie, Wyoming, practice on how they're making the adjustment.

Your eyes lead your body. And because vision is our dominant sense, people notice the difference.

Some patients transition quite nicely through the circadian change. Their body clocks, and sleep patterns, adjust. For others, the change to standard time can exacerbate existing eye conditions and expose undiagnosed vision problems, she says. Doctors of optometry might consider making extra time to query their patients, she adds.

She asks patients: Are your eyes dry? Are you experiencing a burning sensation in your eyes? Is your vision blurry or clear when you blink? When you drive at dusk, dawn or dark, does your clarity and/or depth perception change? Are you confident visually driving to and from work? Do you feel your night vision is satisfactory enough to drive home safely?

Compensating for change

The amount of sunlight people take in through their eyes, transmitted from the retina to the brain via the optic nerve, is an environmental cue for many biological functions. Take sleep, for example. Light and darkness affect how much melatonin your body produces and releases; melatonin affects your sleep cycle.

Most people usually catch up with the disruption caused by daylight saving time in their natural sleep cycle in a matter of a few days. "It all does come down to how exposure to light—blue, of course—affects melatonin release, which is what regulates our circadian rhythms," observes Karl Citek, O.D., Ph.D., chair of AOA's Commission on Ophthalmic Standards and professor of optometry at Pacific University College of Optometry in Forest Grove, Oregon.

"Business travelers who travel between different time zones frequently, and for brief periods, experience this, too," Dr. Citek says. "Many have learned to compensate by changing sleep habits before or during the trip, taking supplements, or, in some cases, taking properly prescribed prescription meds."

An opportunity for doctors of optometry

Still, daylight saving time presents an opportunity for doctors of optometry to reinforce the necessity of comprehensive eye examinations, Dr. Lowe says.

Some patients might experience depression or seasonal affective disorder (SAD), though a recent study questions its existence. Driving home in the darkness, some patients report the distracting glare of oncoming headlights, Dr. Lowe says. Patients with glaucoma and cataracts are especially sensitive, she adds. Some patients complain about blurred vision at night. One possible diagnosis is night myopia, Dr. Lowe says. At night, the pupil's size increases, allowing for more aberrations from uncorrected prescriptions (for glasses and/or contact lenses) due to unfocused or scattered light rays.

"Have you seen old, wavy window panes?" she says. "The distortions or aberrations are similar to that." Then there are environmental factors, brought on by heaters (in your office or car), and stronger, outdoor wind currents that can cause low humidity and lead to dry eye, Dr. Lowe says.

Dr. Lowe suggests doctors of optometry:

Ask patients about how they are making the adjustment to seasonal conditions.